1. Field of the Invention
The present invention relates to an improvement of a knapsack engine-driven tool, such as an engine-driven sprayer or and an engine-driven spray. More particularly, the invention relates to an improved knapsack engine-driven tool having an improvement in which the starting or stopping of the engine and can be made and the rotation speed of the engine can be regulated.
2. Description of the Related Art
As shown in FIG. 4 explaining prior art, the operating portion of the conventional knapsack engine-driven tool E has a knapsack frame A having an engine mounted thereon. The engine is equipped with the frame via a coil spring as a supporting member at a base portion B1 of a lower corner portion A1 of the knapsack frame A. Within the coil spring B, throttle wire C for operating a throttle of the engine and an electric wire for stopping the engine are inserted. To the edge B2 of the spring coil B is connected the edge of the throttle wire C, and a throttle lever is provided for operating it.
By providing such an operating means via a coil spring which can be freely bent, an operator can operate such a means at a position capable of being easily operated by picking it and bent to the desired position.
However, such a construction is disadvantageous in that the movable range is severely restricted not so as to set the position suitable for all of the operators. Also, even if the coil spring can be bent to a desired position, when the operator takes the hand from the coil spring such as at the time of finishing the operation, the coil spring is strongly returned to the original position (vertically), there being a risk to strongly hit the coil spring at the operator as shown on the broken line B' in FIG. 4. Moreover, when the operator wants to operate such an engine again, after the finishing of the operation, it becomes sometimes difficult to pick up the coil spring B' again.
In order to overcome such an disadvantage, Japanese Patent Laid-Open No. 10-299503 discloses the use of a sporting tool made of a semi-rigid material which can be held in a prescribed portion instead of the coil spring. According to this patent application, a shape of the supporting tool of the operating portion can be changed according to the force applied and, the desired shape can be held even after the removal of the force.
However, such a kind of tool is often roughly treated not only during the operation but also in the case of storage and custody. Consequently, in the case of the tool made of the semi-rigid material, the tool becomes defective when it is bumped to deform or destroy the tool, and such a tool is disadvantageous in terms of durability.
Furthermore, in the case of the tool made of the semi-rigid material, there is also problem associated with immediate deterioration due to friction etc., when the operating portion is frequently moved.
Moreover, in the semi-rigid material there is a fear of the change in the rigidity due to the difference in the temperature. In addition, such a tool is often used under severe conditions such as heating generated by the use of the driving source. For these reasons, it is difficult to say that the tool exhibit constant function even under any conditions.
On the other hand, the use of the semi-rigid material requires an expensive cost in terms not only of the material cost but also of the processing cost in comparison with a generally used material such as iron.